The truck drivers, who are alleging widespread work violations by three local trucking companies, have undertaken a limited walkout that is expected to last 48 hours, organizers said.

The union-backed group Justice for Port Truck Drivers launched picket lines at Green Fleet Systems, Total Transportation Services Inc. and Pac 9 Transportation. They also plan to picket the companies’ trucks as they enter the port complex, the largest in the country.

The truckers are directing their protest only at rigs being driven for those three companies.

ILWU members had congregated in a parking lot at the Long Beach Container Terminal awaiting a decision by an arbitrator, who is supposed to determine whether the strike is legitimate. But no arbitrator was available, so the dockworkers went to work.

If the truckers' picket line is ultimately considered a legitimate labor action by an arbitrator, ILWU longshoremen, clerical workers and other members may walk off their jobs.

Truckers and members of Teamsters Local 848 chanted slogans as a queue of trucks waited to enter the terminal.

An ILWU official at the port declined to comment on the situation and instructed members of the union not to speak with reporters.

Art Wong, a Port of Long Beach spokesman, said port officials are monitoring the situation.

Justice for Port Truck Drivers, the union-backed group organizing the strike, has accused trucking companies of wrongfully classifying truck drivers as independent contractors, a classification that denies drivers workplace protections such as overtime and mandated work breaks. It also results in lower pay.

Alex Cherin, a spokesman for the trucking firms and executive director of the Harbor Trucking Assn., issued a statement saying the Teamsters are waging a battle that “a vast majority of harbor truck drivers have soundly rejected time and time again.”

“There are literally hundreds of unfilled vacancies for company drivers throughout Southern California,” Cherin said. “If a driver wants to become an employee, rather than an independent contractor, he or she can do so.”

The strike is the third in the past year. In recent months, tensions have escalated between the trucking companies and drivers, dozens of whom have filed wage-theft complaints with the state labor commissioner’s office.

So far, port drivers in California have filed more than 500 complaints of wage theft related to misclassification, according to the state Department of Industrial Relations. The agency said 32 drivers have won decisions against 13 trucking firms, securing $3.8 million in wages and penalties.

Organizers notched a victory last month when Pacific 9 Transportation, a major trucking company, agreed to post notices acknowledging the workers' right to organize.